This invention relates to a digital memory system for controlling the sorting of articles.
In various production plants today, a variety of products are produced on separate production lines, and the products are then fed onto a common conveyor which delivers the products to a storage area where they accumulate prior to being loaded onto trucks and shipped. In a dairy plant, for example, a series of product-filling machines fill cartons with various products such as milk, buttermilk, cottage cheese, and the like. Each machine discharges stacks of cases filled with separately identifiable products onto a common conveyor which transfers the stacks off cases in a random order from the filling area to a cold storage room where they are removed from the conveyor. Generally, the cases are sorted into groups of like products in the storage area in preparation for shipping.
In the past, products delivered to the storage area have been removed from the conveyor and sorted manually, but this method is too time consuming and costly because it requires an inordinately large expenditure of man-hours, it also requires considerable supervision, and it is seriously lacking in inventory control.
Due to recent developments, dairy plants and other production plants are being equipped with systems for automatically sorting products delivered in a random order to a storage area on a single conveyor from a production area. Generally, such systems include a lug-type indexing conveyor for delivering products from the production area to the storage area, and separate side-by-side storage lanes located in the storage area adjacent the indexing conveyor. Products are sorted as they travel along the lug conveyor and are transferred onto respective preselected storage lanes.
A lug-type indexing conveyor is a recent development in the art, and generally includes a track along which the cases move, and a longitudinally reciprocating carriage below the track for pushing the cases along the track. Pusher lugs are spaced apart along the length of the carriage, and each lug pushes a given stack of cases one step to a position in front of the next lug during each forward stroke of the conveyor carriage. Thus, the stacks of cases move one step at a time along the conveyor track during each reciprocation of the carriage.
Generally speaking, products of a given type are sorted and automatically transferred from the indexing conveyor at predetermined storage lanes where they accumulate prior to being shipped. A common prior art sorting method is the direct coding of the articles for read-out at a subsequent storage station. This method includes a separate code applicator system at each product entrance station on the lug conveyor, and a code reader at each storage lane. Such a method includes coding with glass beads, or soap foam spots, and retroreflective (electric eye) systems for reading the codes at each storage lane. Other methods include direct contact readers, such as electrodes for sensing soap foam spots or the like on each stack of cases. The disadvantage of these systems is that the equipment is costly to install and maintain, particularly for large installations containing numerous product filler stations and a multitude of storage lanes, such as in a dairy plant. Moreover, many product-containing receptacles or cases, particularly milk cases, vary in size or configuration, which makes it especially difficult to directly code and read them accurately. Some cases are made of steel wire and leave no surface for coding with conventional or known means.